Summary of Work: Exposure to highly estrogenic substances can disrupt reproduction and increase cancer risk, as well as influence bone metabolism and cardiovascular health. Chemicals that are weakly estrogenic are widespread in the environment, including several pesticides. Health effects of these environmental estrogens are not known. This project was designed to determine whether a test-case exposure to environmental estrogens, i.e., exposure to dietary soybeans (rich in plant estrogens) had the expected estrogenic effects. The experimental study compared women who were randomized to a soy-diet group with women who ate normally. No estrogenic effects could be definitely determined, though there was a weak (non statistically significant) increase in growth of vaginal cells as measured by vaginal cytology.